title: Flaviviruses are sensitive to inhibition of thymidine synthesis pathways.
abstract: Dengue virus has emerged as a global health threat to over one-third of humankind. As a positive-strand RNA virus, dengue virus relies on the host cell metabolism for its translation, replication, and egress. Therefore, a better understanding of the host cell metabolic pathways required for dengue virus infection offers the opportunity to develop new approaches for therapeutic intervention. In a recently described screen of known drugs and bioactive molecules, we observed that methotrexate and floxuridine inhibited dengue virus infections at low micromolar concentrations. Here, we demonstrate that all serotypes of dengue virus, as well as West Nile virus, are highly sensitive to both methotrexate and floxuridine, whereas other RNA viruses (Sindbis virus and vesicular stomatitis virus) are not. Interestingly, flavivirus replication was restored by folinic acid, a thymidine precursor, in the presence of methotrexate and by thymidine in the presence of floxuridine, suggesting an unexpected role for thymidine in flavivirus replication. Since thymidine is not incorporated into RNA genomes, it is likely that increased thymidine production is indirectly involved in flavivirus replication. A possible mechanism is suggested by the finding that p53 inhibition restored dengue virus replication in the presence of floxuridine, consistent with thymidine-less stress triggering p53-mediated antiflavivirus effects in infected cells. Our data reveal thymidine synthesis pathways as new and unexpected therapeutic targets for antiflaviviral drug development.
authors.affiliation: Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Fischer
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Smith
authors.forename: David
authors.initials: D
authors.lastname: Shum
authors.forename: David A
authors.initials: DA
authors.lastname: Stein
authors.forename: Christopher
authors.initials: C
authors.lastname: Parkins
authors.forename: Bhavneet
authors.initials: B
authors.lastname: Bhinder
authors.forename: Constantin
authors.initials: C
authors.lastname: Radu
authors.forename: Alec J
authors.initials: AJ
authors.lastname: Hirsch
authors.forename: Hakim
authors.initials: H
authors.lastname: Djaballah
authors.forename: Jay A
authors.initials: JA
authors.lastname: Nelson
authors.forename: Klaus
authors.initials: K
authors.lastname: Früh
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004267:DNA Viruses / Q000187:drug effects; D003716:Dengue Virus / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D004195:Disease Models, Animal; D005416:Flavivirus / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D018177:Flavivirus Infections / Q000188:drug therapy; D005467:Floxuridine / Q000494:pharmacology; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D002955:Leucovorin / Q000494:pharmacology; D008727:Methotrexate / Q000494:pharmacology; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D012328:RNA Viruses / Q000187:drug effects; D013936:Thymidine / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014709:Vero Cells; D014779:Virus Replication / Q000187:drug effects; D014902:West Nile virus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
chemical_list: D000998:Antiviral Agents; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D005467:Floxuridine; D002955:Leucovorin; D013936:Thymidine; D008727:Methotrexate